Microstructures and nanostructures are usually created by means of optical lithography. The substrate to be structured is first overlaid with a recording medium. The structure to be created is imparted to this recording medium by locally irradiating the recording medium with light through a mask. It is thereby transformed from an unwritten into a written state which is manifested in altered physical and/or chemical properties of the recording medium. The recording medium is then selectively removed either only at the written sites or only at the unwritten sites, whereupon the substrate can be processed, for instance etched, at the exposed sites.
The minimum size of the structures to be written is defined, for diffraction reasons, by the order of magnitude of the light wavelength. Therefore, in order to reduce the size of the structures, i.e. to improve the spatial resolution, the light wavelength used must be increasingly further reduced. The time-consuming and costly need to create a new mask each time the structure is changed limits the use of optical lithography in practice, especially for the prototypical creation of new structures.
The problem addressed by the invention is therefore that of providing a method for optically imparting a structure to a recording medium, which offers an improved spatial resolution and at the same time does not require the creation of a mask.